Appendix D
Operation of the SCSI
© National Instruments Corp.
D-11
GPIB-SCSI-A User Manual
Physical and Electrical Characteristics
Devices on a SCSI bus are connected in a daisy-chain configuration as
shown in Figure D-2.
SCSI host
GPIB-SCSI-A
SCSI tape
drive
SCSI disk
drive
SCSI disk
drive
Figure D-2. Daisy-Chain Configuration of the SCSI Bus
The SCSI specification details two types of connectors. The connector for
non-shielded cabling, which is normally used for in-cabinet applications, is
a 50-conductor ribbon cable type connector consisting of two rows of 25
female contacts. The second type of cabling is the shielded cable. This 50-
conductor connector consists of two rows of ribbon contacts.
Configuration Restrictions
To achieve the high data transfer rate that the SCSI is designed for, there are
limitations placed on SCSI bus configurations. The SCSI bus can have a
maximum of eight devices connected in a daisy chained configuration and
the total cable length in a SCSI system cannot exceed 6.0 m.
The last device on the SCSI must have terminating resistors, while all other
devices must not have terminating resistors. The only exception to this
occurs when the total length of the SCSI system exceeds approximately 3 ft
or there are multiple devices attached to the SCSI. In this case, two sets of
termination resistors may be required–one set at both ends of the SCSI
configuration.
Содержание GPIB-SCSI-A
Страница 20: ......
Страница 27: ......
Страница 355: ...Appendix C Operation of the GPIB National Instruments Corp C 7 GPIB SCSI A User Manual Figure C 2 Linear Configuration ...
Страница 356: ...Operation of the GPIB Appendix C GPIB SCSI A User Manual C 8 National Instruments Corp Figure C 3 Star Configuration ...